Medication errors and adverse drug events ADE are a constant challenge for healthcare providers. The fast-paced and unpredictable setting of an emergency department is especially prone to errors contributing to 3 of all hospital-related adverse events. This study evaluates the impact of computerized physician order entry CPOE used in conjunction with a decision support system DSS on the prevalence and types of interventions by pharmacy staff during the prescription-filling process in an emergency department ED.